Hi
Without too much technical terms, the Pure Strength series is a set of three tapes, each tape targeting specific muscle groups for example back and biceps or chest, triceps and shoulders, etc..two tapes run about 45 min and the leg one is about an hour. Moderate to heavy weights are used and if i remember correctly each exercise is about 3 sets of 8 -10 repetitions. The Slow and Heavy series again is a set of 3 tapes, each tape targeting a group of muscles, only they run longer..about 1 hr or more each tape and each repetition is sort of like in slow motion. Instead of the usual count, each rep is like 5-6 seconds working the negative and again the positive..so it takes longer..it also works your muscles better I think...i hope this made sense to you. I have both and when i feel i need a tougher workout i do the S&H which is longer, although Pure STrentgh isn't easy either
Vanessa